Next, tonight, a secret inside the modern american family. Almost every parent has at one time or another yelled at a difficult child. And tonight, there is a new study giving insight into what that can do to everyone when an adult starts yelling. "Nightline" anchor cynthia McFADDEN NOW WITH ADVICE FOR THE Whole family. Reporter: Who can say they've never yelled at their kids especially their teenagers? A problem the "super nanny" was often brought in to deal with. You don't tell me anything. You do what I tell you to do and you shut your damn mouth about it. Reporter: And it's not just reality tv. I've been having problems with my daughter. Reporter: The dads at this father's group in new jersey, part of parents anonymous, were honest enough to admit it. How many of you have ever yelled at your child? But a new study contends, even an otherwise loving home, yelling, especially when it is mixed with name calling an insults, can cause the same problem for young teenagers as hitting them. Depression, anxiety and low self-esteem. The johnson-tuggey clan in cleveland say they don't curse or use put-downs, but they could use little help with yelling. I'm a yeller. I yell out of frustration. Like, hey, grab their attention. Sometimes when I get yelled at, I get angry, I start hitting my punching bag or, I feel sad. I just wish I could get talked to, not necessarily yelled at. Reporter: We brought in parents expert, dr. Carolyn ievers-landis. One strategy she suggestions is for parents to give themselves a time-out. Having a parent that is not pushed to the limit as much, maybe step in a little bit. I don't think any parent would ever object to having a break. Reporter: Another tip? Use more carrot, less stick. You want them to get ready for school faster? Promise a movie. Learning to negotiate and keep your cool can make the teen years so much less stressful for everyone. Bye! Reporter: Or, as my mother used to say in a very quiet voice, when you've lost your temper, you've lost your argument. Diane? Your great mother. But what you've ever done it? What are you going to do? Reporter: I love this advice from parents experts who say, don't be afraid to apologize to your kids. You don't lose authority. You actually gain credibility. Parents are people, too. If you apologize, they'll know that apologizing is something we do in our family. So, admits i, apologize. Reporter: Fess up. Thank you so much, cynthia. Next, we are going to show you a human travel ing at 833

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